/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package mobileAPI;

import entity.Courses;
import entity.Enrollment;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import jpa.controllers.CoursesJpaController;
import jpa.controllers.EnrollmentJpaController;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

/**
 *
 * @author Geymen
 */
public class MyCoursesListServlet extends HttpServlet {

    /**
     * Processes requests for both HTTP
     * <code>GET</code> and
     * <code>POST</code> methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    public void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        
        Integer userID;
        userID = Integer.valueOf(request.getParameter("userID"));

        // First get enrollment entities which matches with userID
        EnrollmentJpaController enrollmentJpaController = new EnrollmentJpaController();
        List<Enrollment> enrollmentList = enrollmentJpaController.findEnrollmentEntitiesWithUserID(userID);
        
        //********************************
        
        // Second generate a list of courseIDs
        List<Integer> courseIDList = new ArrayList<Integer>();
        for (Iterator<Enrollment> it = enrollmentList.iterator(); it.hasNext();) {
            Enrollment enrollment = it.next();
            courseIDList.add(enrollment.getCourseId().getCourseId()); 
        }
        
        //********************************
        
        // Third generate a array list with maps containing courseIDs and their descriptions
        CoursesJpaController coursesJpaController = new CoursesJpaController();
        ArrayList coursesMapList = new ArrayList();
        for (Iterator<Integer> it = courseIDList.iterator(); it.hasNext();) {
            Integer courseID = it.next();
            Courses course = coursesJpaController.findCourses(courseID);
            
            Map courseMap = new HashMap();
            courseMap.put("courseID", new Integer(courseID));
            courseMap.put("courseName", new String(course.getName()));
            coursesMapList.add(courseMap);
        }
        
        //********************************
        
        // Forth generate a JSONObject object containts JSONArray
        JSONArray coursesListJSONArray = JSONArray.fromObject(coursesMapList);
        JSONObject respondJSONObject = new JSONObject();
        respondJSONObject.element("myCoursesList", coursesListJSONArray);
        
        try {
            /* TODO output your page here. You may use following sample code. */
//            out.println("<!DOCTYPE html>");
//            out.println("<html>");
//            out.println("<head>");
//            out.println("<title>Servlet MyCoursesListServlet</title>");            
//            out.println("</head>");
//            out.println("<body>");
//            out.println("<h1>Servlet MyCoursesListServlet at " + request.getContextPath() + "</h1>");
//            out.println("</body>");
//            out.println("</html>");
            
            out.println(respondJSONObject);
        } finally {            
            out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP
     * <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP
     * <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}
